Thread-tensioning apparatus



A. A. ATKINS THREAD-TENSIONING APPARATUS Aug 16, 1955 2 Sheets-Sheet 1 Filed Oct. 24, 1952 /m/e/7 for Ar/hu/AmbmseA/k/hs By fills aflomeys Aug. 16, 1955 A. A. ATKINS THREAD-TENSIONING APPARATUS 2 Sheets-Sheet 2 Filed Oct. 24, 1952 F IG.4.

. '/nvenf0r ArfflurAmbrose Aflrlhs By his atforneys United States Patent THREAD-TENSIONING APPARATUS Arthur A. Atkins, Coventry, England, assignor to Courtaulds Limited, London, England, a British company Application October 24, 1952, Serial No. 316,740

Claims priority, application Great Britain November 16, 1951 4 Claims. (Cl. 242-150) This invention relates to thread-tensioning apparatus.

In many textile operations, for example winding, knitting and warping, it is desirable to deliver a textile thread at a constant tension in order to avoid variations in the thread product. In one known type of tensioning device,

the thread is passed between two discs which are suitably L tension device so as to maintain a substantially uniform tension in the thread.

his the object of the present invention to provide a simple automatic thread-tensioning device operating satisfactorily at high speeds.

According to the present invention, a thread-tensioning device comprising two surfaces or two sets of surfaces between which a thread can pass is combined with a guide for the thread mounted at the free end of a cantilever spring which bears on one surface or on one set of surfaces urging it towards the other surface or set of surfaces so that changes in tension of the thread which has passed between the two surfaces or sets of surfaces and then over the guide, vary the pressure of the spring on such surface or surfaces to make compensating changes in the thread tension.

The tensioning device according to the invention may take the form of any of the known types of tensioning device for example the disc or gate tensioning device. In the disc type of device the spring preferably bears directly on one of the discs but if desired a cushioning washer may be provided between the spring and the disc.

In a modification of the tensioning device according to the invention, the free end of the spring bears directly on one of the surfaces or on one set of the surfaces and the surface itself then serves as the guide for the thread. Thus, with a disc tensioning device, the free end of the spring may be attached to the underside of a disc and the disc may then have a V-notch cut into it to serve as a guide for the thread.

In all forms of the invention it is necessary to avoid undue oscillation of the spring and the moving parts of the device should therefore have a high natural frequency relative to the expected causes of tension fluctuation, for example the revolutions per minute of the take-up device for the thread, the cyclic speed of the traverse mechanism on the take-up device and the unwinding speed of the delivery thread package. Such oscillations may be damped by placing oscillation damping means for example, damping grease or a dashpot between the spring and the frame of the device.

The present invention is illustrated by way of examples in the accompanying drawings in which "ice Figure l is a vertical cross-section of one form of the invention applied to a disc tensioning device,

Figure 2 is a plan view of Figure 1,

Figure 3 is a vertical cross-section of a modified form of a disc tensioning device,

Figure 4 is a front elevation of a further form of the invention applied to a gate tensioning device, and

Figure 5 is a plan view of Figure 4, the travelling thread not being shown.

Referring to Figures 1 and 2 of the drawings a support block 1 carries a pigtail guide 2 and a channel frame 3 which forms the base of the device. Two disc pins 4, 5 are mounted on the channel frame 3. Pin 4 supports a spacing sleeve 43 and a ceramic sleeve 44 having a fiange 45 upon which is seated a disc pretensioning device 6 of normal construction. Pin 5 supports a ceramic sleeve 46 over which are loosely placed two discs 7a, 7b of an automatically compensating disc tensioning device 7 constructed according to the present invention. The upper disc 7a of the device 7 is fixed to an adjusting knob 8, suitably made of brass, which screws on to a threaded portion 47 of the disc pin 5 to set the position of the disc 7:: and so determine the nominal tension. The lower disc 71: bears against a cantilever spring 9 which is fixed to the channel frame 3 by screws 10. A damping grease 13 is placed between the spring 9 and the channel frame 3 and the cantilever spring 9 has a V-shaped guide 12 at its free end. A locking spring 14 of usual construction is fitted to disc tensioning device 7 and bears on the knob 8 which is knurled, to prevent its accidental displacement.

The method of operation is as follows:

A thread 15 is led through the pigtail guide 2 and the pretensioner 6, through the disc tensioning device 7 to the guide 12 where it is deflected through about An increase in tension of the yarn thus tends to depress the spring 9 and relieve the pressure of it on the lower disc 7b. The disc 7b is then free to move away from the disc 7a and so lower the tension on the yarn 15. The upper disc 7a which is fixed to the brass adjusting knob 8 is preset to the desired nominal tension and held in place by the locking spring 14. The damping grease 13 serves to prevent resonance of the cantilever spring 9 particularly at high delivery speeds.

Figure 3 shows a modification of the device shown in Figures 1 and 2 in which the lower disc 7b is fixed permanently to the cantilever spring 9 and the yarn is turned through 90 over the edge of the lower disc 717 or over a V-shaped notch cut into this edge. An auxiliary guide 16 is fixed to the channel frame 3 in this modification. Apart from these modifications, the apparatus is as shown in Figure 1.

The pre-tensioning device 6 shown in the drawings may be dispensed with in certain textile operations.

The damping grease 13 may be replaced by sponge rubber pads or by a dashpot suitably fixed to the channel member 3, the piston in the dashpot being fixed to the spring 9 and passing through a clearance hole in the channel member 3.

In Figures 4 and 5, a support block 17 forming the body of the tensioning device carries a pigtail guide 18 and a disc pretensioning device 19 of normal construction. A cantilever spring 20 is mounted on the block 17 by means of screws 21 and extends along and above the block 17 ending in a V-shaped thread guide 22 above a V-shaped cut-out 23 in the block 17. One member 24 of a gate tensioning device, indicated generally at 25, is mounted on the upper side of the spring 20 adjacent the guide 22 and co-operates with a second member 26 of the gate tensioning device which is supported by a plate 27 bolted to the block 17. A wire thread guide 28, bent to define a vertical slot, is fixed by one end to the plate 27, the other end being located in a hole 29 in the block 17. A screw 30 passes vertically through the block 17 and presses against the underside of the spring 20. The screw 30 is provided with a cylindrical head 31 fitted with a knurled jacket 32 housed in a recess 33 in the block 17. The recess 33 has cut-away slots 34 to permit manual manipulation of the head 31. A channel 35, opening into the recess 33 houses a ball 36, urged into contact with the jacket 32 by means of a spring 37 enclosed within the channel 35 by a grub screw 38. The ball 36 normally offers resistance to the free movement of the screw 30 but permits the screw 36 to be turned by hand by means of the head 31. In order to avoid undue oscillation of the spring 20, a dashpot 39 with a cover 49 is provided in the block 17. A plunger 41 suspended from the spring 20 passes through an opening in the cover 49 into a fluid, for example oil,

provided in the pot 39.

The operation of the deviceis similar to that described above in relation to the form using the disc tensioning device. A travelling thread 42 passes over the guide 18 to the gate tensioning device 25 through the pre-tensioning device l 9 and the guide 23. In the tensioning device 25, the thread 42 is caused to pass through a zig-zag path before being guided through the cut-out 23 by means of the guide 22. The thread 42 is pre-tensioned by the device 19 and is also tensioned by the device 25 by an amount depending upon the degree of co-operation between the members 24, 26. The tension imparted to the thread 42 is substantially predetermined by the pressure exerted by the screw 39 on the spring 20. If the tension should exceed the predetermined amount, the member 24 is pulled down against the spring 20 by the thread 42 passing over the guide 22 and the tension on the thread 42 is decreased as the zig-zag path tends to smooth out. If the tension should fall below the predetermined amount, the member 24 rises under the action of the spring 20 and the zigzag path becomes more acute thus increasing the tension. Consequently, the tension of the thread 42 leaving the device is substantially constant and is automatically maintained at a predetermined value set by the screw 30. For certain textile operations, the pre-tensioning device 19 may be omitted. 7

What I claim is:

l/A thread tensioning device for maintaining a substantially constant tension in a travelling thread comprising a frame, a cantilever spring mounted on one end of the frame, extending above and toward. the other end of the frame, a pair of cooperating surfaces located adjacent to the free end of the spring, the first surface being held in a fixed position and the second surface being supported by the spring in the vicinity of its free end and being urged toward the first surface by the resilience of the spring, the two surfaces thereby leaving a passage therebetween for the thread which offers resistance to the thread, oscillation damping means placed between the spring and the frame to damp undue oscillations in the spring, and a thread guide at the free end of the spring over which the thread passes, leaving it at an angle which causes the thread to 'be'ar downwardly on the free end, whereby changes in tension of the thread, which has passed through the passage defined between the surfaces and then over the guide, oppose the action of the spring to make compensating changes in the yarn tension.

2. A thread tensioning device as claimed in claim 1 in which the resilience of the spring is predetermined by a manually adjustable screw.

3. A thread tensioning device for maintaining a substantially constant tension in a travelling thread comprising a frame, a cantilever spring mounted on one end of the frame, extending above and toward the other end of the frame, a pair of cooperating discs located adjacent to the free end of the spring, the first disc being held in a fixed position and the second disc being supported by the spring in the vicinity of its free end and being urged toward the first disc by the resilience of the spring, the two discs thereby leaving a passage therebetween for the thread which offers resistance to the thread, a mass of grease wedged between the spring I and the frame at a point midway along the spring to damp undue oscillations in the spring, and' a thread guide at the free end of the spring over which the thread passes, leaving it at an angle which causes the thread to bear downwardly on the free end, whereby changes in tension'of the thread, which has passed through the passage defined between the discs and then over the guide, oppose the action of the spring to make compensating changes in the yarn tension.

4. A thread tensioning device for maintaining a substantially constant tension in a travelling thread comprising a frame, a cantilever spring mounted on one end of the frame, extending above and toward the other end of the frame, a pair of cooperating sets of surfaces located adjacent to the free end of the spring, the first set of surfaces being held in a fixed position and the second set of surfaces being supported by the guide at the free end of the spring over which the thread passes, leaving it at an angle which causes the thread to bear downwardly on the free end, whereby changes in tension of the thread, which has passed through the passage defined between the sets of surfaces and then over the guide, oppose the action of the spring to make compensating changes in the yarn tension.

References Cited in the file of this patent UNITED STATES PATENTS Remy Mar. 27, 1883 Wood May 27, 1890 

